A number of systems and programs are offered on the market for the design, the engineering and the manufacturing of objects. CAD is an acronym for Computer-Aided Design, e.g. it relates to software solutions for designing an object. CAE is an acronym for Computer-Aided Engineering, e.g. it relates to software solutions for simulating the physical behavior of a future product. CAM is an acronym for Computer-Aided Manufacturing, e.g. it relates to software solutions for defining manufacturing processes and operations. In such computer-aided design systems, the graphical user interface plays an important role as regards the efficiency of the technique. These techniques may be embedded within Product Lifecycle Management (PLM) systems. PLM refers to a business strategy that helps companies to share product data, apply common processes, and leverage corporate knowledge for the development of products from conception to the end of their life, across the concept of extended enterprise. The PLM solutions provided by Dassault Systèmes (under the trademarks CATIA, ENOVIA and DELMIA) provide an Engineering Hub, which organizes product engineering knowledge, a Manufacturing Hub, which manages manufacturing engineering knowledge, and an Enterprise Hub which enables enterprise integrations and connections into both the Engineering and Manufacturing Hubs. All together the system delivers an open object model linking products, processes, resources to enable dynamic, knowledge-based product creation and decision support that drives optimized product definition, manufacturing preparation, production and service.
In this context, there is a need to search existing mechanical parts in a database according to a user-defined criterion, notably where parts are modeled by solids. Searching parts in a database according to a predefined criterion is generally performed through three steps. The first step is to compute and associate to each solid of the database a so-called “signature” (or “descriptor”). A signature is a compact information that synthetizes a typical aspect of the part. The second step if for the user to specify a request/query by setting a signature, and the goal is to find parts that match this signature in the database. Similarly, the signature in the query can be the one of a part being designed and the goal is, again, to find similar parts on the database. The third step is the searching step. It amounts for the system to find parts of the database the signatures of which correspond to the user-input signature. Signatures are massively compared during this step. The signature is advantageously designed to require a small amount of memory, to be easy to compute and to be very rapid to compare.
Existing signatures for shape description may often be based on spherical functions. For specialized domains such as mold design, a dedicated signature may involve material, process, and geographical information. For precise solid comparison, the signature may sometimes include geometrical information closely related to the boundary description of the solids. The following is a list of known solutions that allow querying a database of mechanical parts with such criteria:                1. Document EP 2169567 A2;        2. Rotation Invariant Spherical Harmonic Representation of 3D Shape Descriptors. M. Kazhdan, T. Funkhouser, and S. Rusinkiewicz, Eurographics Symposium on Geometry Processing (2003); and        3. A search engine for 3D models. T. Funkhouser, P. Min, M. Kazhdan, J. Chen, A. Halderman, D. Dobkin, D. Jacobs, D.: ACM Transactions on Graphics 22(1), 83-105 (2003).        4. Efficient 3D shape matching and retrieval using a concrete radicalized spherical projection representation, P. Papadakis, I. Pratikakis, S. Perantonis, T. Theoharis, Pattern Recognition 40 (2007) 2437-2452        5. Comparing 3D CAD Models: Uses, Methods, Tools and Perspectives, Antoine Brière-Côté, Louis Rivest and Roland Maranzana, Computer-Aided Design & Applications, 9(6), 2012, 771-794; and        6. Msaaf, O., Maranzana, R.; Rivest, L.: Part data mining for information re-use in a PLM context, Proceedings of GT2007, May 14-17, Montreal, Canada, ASME Paper: GT2007-27966, American Society of Mechanical Engineers, New York, N.Y., 2007.        
Despite the existing literature, there is still a need for improving the field of searching mechanical parts in a database.